The present invention relates to telecommunications systems and, particularly, to an improved notification system and method for cellular telephones.
Many users rely on one or more portable devices, such as pagers and cellular telephones, to maintain a telecommunications link while traveling. Pagers are advantageous in that they are small and consume relatively little battery power. For example, a pager can typically run as long as a month on a single AA battery. In addition, the cost of maintaining a pager service is typically minimal. However, pagers do not allow for duplex communication.
Cellular telephones, on the other hand, have been developed which are extremely small, but consume large amounts of battery power. For example, a cellular telephone can discharge its battery in a single day even in standby mode waiting for a call to be received. Thereafter, several hours are required to recharge the battery.
Often, users carry both a pager and a cellular telephone. The pager is maintained as an initial notification device. When a call is received on the pager, typically a return phone number is delivered, either manually or by a caller-ID mechanism. To return the call, the user must then turn on the cell phone and dial the number. To enhance such usability, pagers and cellular phones have been developed which are packaged together in the same housing. In particular, U.S. Pat. Nos. 5,737,707 and 5,802,470 describe a personal communications device including both a pager and a cellular telephone. The cellular telephone is normally kept off and draws no power. When an incoming call for the cellular telephone arrives at the cellular exchange, and it is determined that the cellular phone has not been registered with a base station, a paging system transmits a paging signal to the integrated pager. The pager receives the signal and wakes the cellular telephone, which then processes the call. When the call is completed, a second paging message is provided, and the cellular telephone shuts down.
While the system described in the ""707 and ""470 patents is useful in conserving battery power, it is still possible for the cellular telephone to draw too much power and cause the paging system to have to shut down (even though the pager draws much less power than the cell phone).
Accordingly, there is a need for a combined cellular telephone/pager wherein power may be conserved and messaging capabilities preserved.
These disadvantages in the prior art are overcome in large part by a system and method according to the present invention. According to one aspect of the invention, a cellular phone and a pager having a common battery are integrated into a single unit. The unit is maintained in a low-power receive page mode when not in use. An incoming call is processed first as a conventional pager message. The device receives the page and wakes from the low-power page mode. When the device has gone to full-power active mode, a cellular phone call is connected. A smart battery controller for the unit is provided. The smart battery controller monitors the power level left in the battery and stops allowing phone operations when power reaches a minimum level. For example, the level may be configurable by the user as the number of hours of paging that may be accommodated after cell phone operations are no longer permitted.
A better understanding of specific embodiments of the invention is obtained when the following detailed description is considered in conjunction with the following drawings.